Known hard disk drives consist of one or more discs which are provided with magnetisable material in an annular pattern on one or both flat sides of the discs. Hard disk drives comprise at least one read/write unit in order to read-out the magnetised pattern. At present unpatterned discs are used exclusively.
Due to the increasing demand for ever greater bit density, it is desirable to reduce the dimensions of the magnetisable layer applied to the discs.
Magnetisable patterns for patterned discs (known as “patterned media”) may theoretically also be produced by stamping methods, in which, for example, a robotic arm, generally centrally gripping the centre hole of a disc, places said disc on a die and the die located above is guided, after adjustment, onto the disc below, the disc being stamped by application of considerable mechanical pressure of from 10 N/cm2 to 100 kN/cm2 to the polymer material to be stamped of the discs.
When using quartz dies considerable stamping forces are also required, as is a considerable curing time for the material, which considerably restricts throughput when producing the discs and thus causes production costs as well as the production speed to increase considerably.
Further drawbacks of the methods described are the adjustment accuracy of the dies due to the elevated forces to be applied to the disc, as well as problems caused by soiling of the die.
In storage discs of this type, it is also important that the concentric patterns are aligned with a high degree of accuracy exactly with the rotational axis of the storage discs. A non-centred transfer would make it impossible to guide the read head of a hard disk drive, since it is conventional for the rotational speed to be greater than 7,000 revolutions per minute.
In storage discs which are patterned on both sides, it is necessary for the patterns on the second side to correspond as exactly as possible to the patterns on the first side.